1. Field
Aspects of the present invention relate to an image forming apparatus. More particularly, aspects of the present invention relate to an arrangement of parts of an image forming apparatus which causes the image forming apparatus to have a compact size.
2. Description of the Related Art
Generally, image forming apparatuses, (especially electro photographic image forming apparatuses such as laser printers), include a printing medium supplying unit that holds printing media (such as sheets of paper), picks up the printing media one by one, and supplies the picked up printing medium; a feeding roller that supplies the printing medium picked up from the printing medium supplying unit; an image forming unit that forms images corresponding to printing data on the printing medium fed by the feeding roller, a fixing unit that fixes the images formed onto the printing medium by the image forming unit; and a discharging unit that discharges the printing medium as the printing medium passes through the fixing unit to the outside thereof.
The conventional image forming apparatuses including above-described parts may be classified into two types which have different basic structures according to an arrangement of parts thereof: an “S” type and a “C” type. The “S” type is an image forming apparatus that has a printing medium moving path which is similar to the shape of the letter “S.” The “C” type is an image forming apparatus that has a printing medium moving path which is similar to the shape of the letter “C”.
FIG. 1 shows an “S” type conventional image forming apparatus 10. Referring to FIG. 1, a printing medium supplying unit 11 is disposed at a low vertical position of the image forming apparatus 10. A feeding roller 13, an image forming unit 15, and a fixing unit 17 are disposed in a row above the printing medium supplying unit 11. According to this structure, the feeding roller 13, the image forming unit 15, and the fixing unit 17 are disposed in such a way that the positions at which a printing medium passes through each of the feeding roller 13, the image forming unit 15, and the fixing unit 17 are at approximately the same horizontal level. Alternatively, the feeding roller 13, the image forming unit 15, and the fixing unit 17 are disposed in such a way that the positions at which a printing medium passes through are slightly upwardly inclined from the feeding roller 13 to the fixing unit 17.
The exposure unit 16 irradiates laser beams corresponding to printing data onto a photosensitive medium 15a of the image forming unit 15. The exposure unit 16 is disposed above the image forming unit 15. A feed guiding part 12 is disposed between the printing medium supplying unit 11 and the feeding roller 13 to divert a printing medium from its feeding direction, so that the printing medium picked up at the printing medium supplying unit 11 is fed to the feeding roller 13. An auxiliary printing medium supplying unit 14 is disposed at a side of the feeding roller 13 to feed special kinds of printing medium, such as envelopes, into the image forming apparatus 10.
A discharging unit 18 is disposed above the fixing unit 17. Printing media discharged from the discharging unit 18 are piled up at a printing medium storing part 19 disposed above the exposure unit 16. Also, a discharge guiding part 18a is disposed between the discharging unit 18 and the fixing unit 17 to divert a printing medium from its feeding direction, so that the printing medium which passes through the fixing unit 17 is fed to the discharging unit 18.
Therefore, the printing medium supplying unit 11 picks up printing media one by one, and the feed guiding part 12 diverts each of the printing media from its feeding direction to feed the printing media to the feeding roller 13. The feeding roller 13 feeds the printing medium to the image forming unit 15. At this time, the exposure unit 16 forms electrostatic latent images corresponding to printing data on the photosensitive medium 15a of the image forming unit 15, and the image forming unit 15 develops the electrostatic latent images into images using toner.
The images formed on the photosensitive medium 15a of the image forming unit 15 are transferred onto a printing medium as the feeding roller 13 moves the printing medium between the photosensitive medium 15a and the transferring roller 15b. When the printing medium with the transferred images passes through the fixing unit 17, the images are fixed onto the printing medium. Then, the printing medium with the fixed images moves along the discharge guiding part 18a to the discharging unit 18. The printing medium is discharged onto the printing medium storing part 19 disposed above the exposure unit 16 and the image forming unit 15, and the printing work is completed.
However, because a printing medium has to change a feeding direction twice during the printing work, it is difficult to design an “S” type image forming apparatus 10 which has a structure having a lower height and a shorter length. Also, it is difficult to design an “S” type image forming apparatus 10 which has a compact size because there are some dead spaces that cannot be used, such as a first space 21 between the feeding roller 13 and the printing medium storing part 19, and a second space 22 between the exposure unit 16 and the fixing unit 17, as illustrated in FIG. 1.
Referring to FIG. 2, a “C” type conventional image forming apparatus 30 includes a printing medium supplying unit 31 disposed at a low position therein. A feeding roller 33, an image forming unit 35, and a fixing unit 37 are vertically disposed in a row above the printing medium supplying unit 31. An auxiliary printing medium supplying unit (not shown) may be disposed above the printing medium supplying unit 31 to feed special kinds of printing media, such as envelopes, into the image forming apparatus 30. A discharging unit 38 is disposed above the fixing unit 37, and discharges printing media to a printing medium storing part 39 disposed above the image forming unit 35. An exposure unit 36 is disposed at a side of the image forming unit 35 to form electrostatic latent images on a photosensitive medium 35a. 
Therefore, the printing medium supplying unit 31 picks up printing media loaded therein one by one and feeds the sheets of printing media to the feeding roller 33. The feeding roller 33 feeds each of the printing media to the image forming unit 35. At this time, the exposure unit 36 forms electrostatic latent images corresponding to printing data on the photosensitive medium 35a of the image forming unit 35, and the image forming unit 35 develops the electrostatic latent images into images using toner. The transferring roller 35b transfers the images formed on the photosensitive medium 35a of the image forming unit 35 onto a printing medium passing between the photosensitive medium 35a and the transferring roller 35b. While the printing medium with the transferred images passes through the fixing unit 37, the images are fixed onto the printing medium. The discharging unit 38 discharges the printing medium with the fixed images to the printing medium storing part 39, and the printing work is completed.
Because a printing medium has to change its feeding direction only once during the printing work, the “C” type image forming apparatus 30 may be designed to have a shorter length than the length of the “S” type image forming apparatus 10. However, because the printing medium supplying unit 31, the image forming unit 35, the fixing unit 37, and the discharging unit 38 are vertically disposed in a line, the “C” type image forming apparatus 30 has a higher height. Also, it is difficult to design a “C” type image forming apparatus 30 which has a compact size because there are some dead spaces that cannot be used, such as a third space 41 between the printing medium supplying unit 31 and the exposure unit 36, and a fourth space 42 between the exposure unit 36 and the printing medium storing unit 39, as illustrated in FIG. 2.
Furthermore, in each of the conventional “S” type and “C” type image forming apparatuses 10 and 30, printing media are discharged to the printing medium storing parts 19 and 39 formed at top surfaces of the image forming apparatuses 10 and 30, respectively, so that the image forming apparatuses 10 and 30 should have printing medium supporting plates 19a and 39a, respectively, to prevent the discharged printing medium from falling to the floor. The use of these printing medium supporting plates 19a and 39a increases the number of parts of the image forming apparatuses 10 and 30.
Also, because a printing medium is discharged through a top surface of the image forming apparatuses 10 and 30, users cannot use a space above the top surface of the image forming apparatus 10 and 30, which is also a problem.